Flavobacterium hydrophilum sp. nov. and Flavobacterium cheongpyeongense sp. nov., isolated from freshwater.

ABSTRACT

Two Gram-stain-negative, non-motile, yellow-pigmented bacterial strains, designated IMCC34758T and IMCC34759T, were isolated from freshwater. Phylogenetic analysis based on 16S rRNA gene sequences showed that the two strains formed a distinct clade within the genus Flavobacterium and they shared 97.9 % sequence similarity. The average nucleotide identity (ANI) and digital DNA-DNA hybridization values (dDDH) between the two strains were 85.5 and 30.2 %, respectively, indicating that they are separate species. The two strains showed ≤98.5 % 16S rRNA gene sequence similarities, 80.6-81.3 % of ANI and 24.7-25.1 % of dDDH values to closely related species of the genus Flavobacterium, indicating that the two strains each represent novel Flavobacteriumspecies. The respiratory quinone detected in both strains was menaquinone-6 (MK-6). The major polar lipids of the two strains were phosphatidylethanolamine, an unidentified aminolipid, an unidentified aminophospholipid and an unidentified polar lipid. The DNA G+C contents of strains IMCC34758T and IMCC34759T were 34.0 and 34.1 mol%, respectively. The major fatty acids of the two strains were very similar to each other, comprising iso-C15  0, iso-C15  1 G, anteiso-C15  0 and summed feature 3 (C16  1 ω6c and/or C16  1 ω7c). Phenotypic characteristics including enzyme activities and carbon source utilization differentiated the two strains from other Flavobacteriumspecies. Based on these results, strains IMCC34758T and IMCC34759T were considered to represent novel species in the genus Flavobacterium, for which the names Flavobacterium hydrophilum (IMCC34758T=KACC 19591T=NBRC 113423T) and Flavobacterium cheongpyeongense (IMCC34759T=KACC 19592T=NBRC 113424T) are proposed, respectively.